Abiotic stressors such as drought, salinity, cold, flood and chemical pollution significantly limit crop production worldwide. Cumulatively, these factors are estimated to be responsible for an average 70% reduction in agricultural production. Soil salinity is an abiotic stress that impacts crop yield worldwide and restricts the use of otherwise arable land (Zia et al. 2011. Journal of Medicinal Plants Research. 5(25):6040-6047). However, there are currently no economically sustainable and effective methods for overcoming problems associated with soil salinity as it relates to crop production.
Several studies have shown that the effects of cytotoxicity induced by salt stress can be ameliorated by the exogenous application of chemical compounds such as glycerol (Kaya et al. 2013. Acta Botanica Croatica 72(1):157-168); salicylic acid (Tufail et al. 2013. Pakistan Journal of Botany 45(1):75-82); and kinetin [KIN] and indoleacetic acid [IAA] (Kaya et al. 2010. Turkish Journal of Agriculture and Forestry 34(6):529-538; Kaya et al. 2010. Journal of Plant Nutrition. 33(3):405-422). Other studies have shown that when phosphorous supply is sufficient, inoculation with fungus enhances salinity tolerance by other mechanisms (Gu et al. 2000. Journal of Plant Resources and Environment. 9(2):22-26).
Another approach is production of salt tolerant transgenic plants through incorporation of salt tolerant genes such as the TaHAK1 gene (YuXiang et al. 2011. Journal of Triticeae Crops 31(6):1014-1019), the AtSAT32 gene (MinYoung et al. 2009. Physiologia Plantarum 135(4):426-435.), and the MBF1a gene (MinJung et al. 2007. Biochemical and Biophysical Research Communications. 354(2):440-446.).
Still other studies have suggested that seed priming with NaCl may be a reliable procedure to increase the maize salinity tolerance (Frahbakhsh and Saiid. 2011. African Journal of Agricultural Research. 6(28):6095-6099.).
Breeding new salt tolerant maize varieties presents an effective way to improve the total output of maize and to use salinized soil effectively (Dong et al. 2010. Chinese Agricultural Science Bulletin. 26(10):246-249; Nitsch, J P. 1950. Am J Botany. 37:211-215). However, salt tolerance is a complex trait which is difficult to breed for in plants.